中国致密油评价标准、主要类型、基本特征及资源前景

Assessment criteria,main types,basic features and resource prospects of the tight oil in China

致密油是指以吸附或游离状态赋存于生油岩中,或与生油岩互层、紧邻的致密砂岩、致密碳酸盐岩等储集岩中,未经过大规模长距离运移的石油聚集。在明确了致密油的概念和内涵基础上,提出了10项评价致密油的关键指标。据孔隙度与渗透率划分出3类致密油储层。根据致密油层与生油岩层紧密接触的成因关系,确定了3种致密油类型:①湖相碳酸盐岩致密油;②深湖水下三角洲砂岩致密油;③深湖重力流砂岩致密油。中国致密油分布广泛,目前在鄂尔多斯盆地三叠系延长组长6—长7段、准噶尔盆地二叠系芦草沟组、四川盆地中-下侏罗统、松辽盆地白垩系青山口组—泉头组等获得了一些重要的勘探发现。分析未来致密油发展前景,运用资源丰度类比法初步预测中国致密油地质资源总量(106.7～111.5)×108t,是中国未来较为现实的石油接替资源。

The tight oil refers to an oil that accumulates in source rocks in a free or adsorbed state or in tight sandstones and carbonates interbedded with or adjacent to source rocks.Generally,this oil accumulation has not yet experienced a large-scale,long-distance migration.Based on the clarity of the tight oil concept and connotation,we proposed ten key indices to evaluate the tight oil.Tight oil reservoirs can be generally divided into 3 different types based on porosity and permeability,while the tight oil itself can be also classified into 3 types depending on the genetic relationship of a close contact between tight reservoirs and source rocks,i.e.①tight oil in lacustrine carbonate rocks;②tight oil in deep-lake gravity flow sandstones and ③tight oil in deep-lake delta sandstones.The tight oil is widely distributed in China,currently,a number of important exploration discoveries of the tight oil have been achieved in the Triassic Chang-6 and Chang-7 sections of Yanchang Formation in the Ordos Basin,the Permian Lucaogou Formation in the Junggar Basin,the Middle-Lower Jurassic of the Sichuan Basin and the Cretaceous Qingshankou-Quantou Formation of the Songliao Basin.To expect the tight oil prospect in China,we preliminary forecast that the tight oil geological resources in China are about（106.7~111.5） ×108t.Combined with the analysis of future prospects of petroleum development,we can come to a conclusion that the tight oil in China should be a realistic replacement resource of the conventional oil.